A8503 Datasheet, PDF (1/17 Pages) Allegro MicroSystems – High Efficiency 6-Channel, 2 MHz, WLED/RGB Driver

A8503
High Efficiency 6-Channel, 2 MHz, WLED/RGB Driver for
Medium Displays, with Integrated 55 V Power Switch
Features and Benefits
▪ Active current sharing between LED strings for ±0.6%
accuracy and matching
▪ Drives up to 12 series × 6 parallel = 72 LEDs (V_f = 3.2 V,
I_f = 20 mA) at 5 V
▫ Each individual current sink is capable of 32 mA
▫ Adjustable overvoltage protection (OVP)
▪ 600 kHz to 2 MHz adjustable switching frequency
▫ Open or shorted LED string protection
▫ Open Schottky diode protection
▫ Overtemperature, cycle-by-cycle current limit,
undervoltage, and soft start time-out protections
▫ Selectable latched/auto-restart protection modes
▪ No audible MLCC noise during PWM dimming
▪ No pull-up resistors required for LED modules that use
ESD capacitors
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Package: 26 contact MLP/QFN (suffix EC)
Description
The A8503 is a multi-output WLED/RGB LED driver for
medium-size LCD backlighting. It integrates a current-mode
boost converter with internal power switch and six current
sinks. The boost converter can provide output voltages up to
47 V. The boost converter can drive up to 72 LEDs at 20 mA
per LED with a battery voltage down to 5 V. The LED sinks
are capable of sinking up to 32 mA each, and can also be
paralleled together to achieve even higher LED currents. The
A8503 provides protection against overvoltage, open diode,
open or shorted LED string, and overtemperature. A dual
level cycle-by-cycle current limit function provides soft start
and protects against overloads. A soft start timeout monitor is
provided to enhance protection when starting up into a fault
condition.
When the MODE pin is set low, the A8503 latches on a fault,
and can be re-enabled only by cycling the input voltage, V_IN,
or by toggling the EN pin. Connecting the MODE pin high
provides auto-restart after fault events. The A8503 features
Approximate size
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Applications
▪ Notebook and sub-notebook displays
▪ LCD monitors
▪ LCD panels
Typical Application
V_BAT
5 to 22 V
V_IN
4.3 to 5.5 V
C_BAT
4.7 μF
35 V
VIN
D1
L1
10 μH
R_OVP C_OUT
2.2 μF
SW SW OVP
R_PULLUP
FAULT
C_IN
0.1 μF
R_FSET
C_COMP
1 μF
EN
Shutdown Enable
FAULT
FSET
COMP
EN
MODE
A8503
PAD
LED1
LED2
LED3
LED4
LED5
LED6
PWM
LED State
Off Off Off On Off
R_ISET
PWM
ISET _{AGND PGND PGND DGND LGND}
8503-DS
Figure 1. Typical application circuit